1. Field of the Invention
The present invention relates to metal, and more particularly, to aluminum baseball bats which currently are used at the college and lower levels. Such bats typically include a metal shell formed of aluminum or titanium alloy or other metals, such bats being used not only in baseball but also in softball at such substantially all levels of non-professional levels of play. As referred to herein, the terms xe2x80x9caluminumxe2x80x9d and xe2x80x9ctitaniumxe2x80x9d are intended to encompass the metals and alloys and mixtures of metals and alloys formulated for the manufacture of bat shells.
Recently, the National Collegiate Athletic Association (NCAA) has indicated that, for player safety reasons, the batted ball exit speed for non-wood bats should equate to or not exceed the highest average exit speed using major league baseball quality, 34 inch solid wood bats. Bats meeting these specifications are expected to result in lower incidences of harm to ball players and moderate the game offense.
2. Prior Art
U.S. Pat. No. 5,593,158 issued Jan. 14, 1997 to Filice, et al discloses a hollow aluminum shock attenuating ball bat comprised of essentially two longitudinally extending pieces and a knob and barrel end plug.
U.S. Pat. No. 5,395,108 Souders, et al issued Mar. 7, 1995 for a SIMULATED WOOD COMPOSITE BALL BAT comprises a fiber reinforced composite shell filled with expansible urethane foam to develop compressive stresses therebetween.
U.S. Pat. No. 5,364,095 issued Nov. 15, 1994 to Easton, et al discloses a tubular metal ball bat internally reinforced with fiber composite.
U.S. Pat. No. 5,114,144 issued May 19, 1992 to Baum discloses a composite baseball bat made to look like a wood bat by using a central core of foamed plastic (foam density of 5-15 lbs/cu. ft.) or extruded aluminum covered with a layer of resin impregnated fiber knitted or woven cloth and a surface layer of longitudinally extending planks or strips of resin coated wood veneer.
U.S. Pat. No. 5,460,369 issued Oct. 24, 1995 to Baum discloses a composite bat having a wood veneer surface bonded to a composite tubular core.
U.S. Pat. No. 5,533,723 issued Jul. 9, 1996 to Baum discloses a composite bat having a wood veneer surface and intermediate composite layer bonded to a tubular core of composite or aluminum. The core may comprise a resilient urethane foam and a cavity may be left in the core in the hitting area and the cavity may be filled with less dense material. The core may vary in density over the length of the bat, preferably with a higher density section near the barrel end.
U.S. Pat. No. 5,458,330 issued Oct. 17, 1995 to Baum discloses a composite bat having a wood veneer surface and cavitied foam core.
The primary objective of the invention is to provide a durable metal shell baseball bat in which the ball rebound characteristics approximate those of a wood bat by emulating the longitudinal flexibility and cross sectional rigidity characteristics of a wood bat of similar size and shape whereby the speed of the batted ball is approximately the same as would be experienced with a wood bat of similar weight, shape and size.
The present invention provides a governed performance metal shell ball bat comprising:
a) a metal shell having a maximum outside diameter in the ball hitting area and a ratio of said maximum outside diameter to the wall thickness of the shell in the hitting area in the range of from 40:1-90:1; and
b) a filler substantially filling the interior of the bat shell in the hitting area, said filler having a density in the range of 10-30 lbs./cu. ft. and a hardness on a Shore D test apparatus in the range of 25-65.
The present invention further provides a governed performance aluminum shell ball bat comprising:
a) an aluminum alloy shell having a ratio of maximum outside diameter to the wall thickness of the shell in the ball hitting area in the range of from 45:1-75:1; and
b) a foam material substantially filling the interior of the bat shell in the hitting area, said foam having a density in the range of 10-30 lbs./cu. ft. and a hardness on a Shore D test apparatus in the range of 40-65, said bat having longitudinal flexibility characteristics approximating those of a wood bat of identical geometry.